Preparation / Directions:

Make the cake Line a lightly greased 15- by 10 1/2-inch jelly-roll pan with= foil and grease the foil. Line the foil with wax paper and grease the= paper. In the top of a double boiler set over barely simmering water melt= the chocolate with 1/4 cup water, stirring until the mixture is smooth, and= let the mixture cool for 10 minutes. In a large bowl with an electric= mixer beat the egg yolks with 1/3 cup of the sugar for 5 minutes, or until= the mixture is thick and pale and ribbons when the beaters are lifted, and= beat in the chocolate mixture and the vanilla.
In another large bowl beat the egg whites with the salt until they are= frothy, add the cream of tartar, and beat the whites until they hold soft= peaks. Add the remaining 1/3 cup sugar, a little at a time, and beat the= whites until they just hold stiff peaks. Stir one fourth of the whites= into the chocolate mixture and fold in the remaining whites gently but= thoroughly. Pour the batter into the prepared pan and spread it evenly= with a metal spatula. Bake the cake in the middle of a preheated 350=F8F. = oven for 12 to 15 minutes, or until it is puffed and just set. Let the= cake cool completely in the pan on a rack. (The cake will be puffed when= it comes out of the oven but will sink as it cools.) Make the filling In a= small saucepan sprinkle the gelatin over 2 tablespoons cold water and let= it soften for 5 minutes. Heat the mixture over moderately low heat,= stirring, until the gelatin is dissolved, and let it cool for 5 minutes. = In a bowl combine the cream, the espresso pow! ! der, and the cinnamon and= beat the mixtur e until it holds soft peaks. Add the confectioners' sugar,= sifted, and the gelatin mixture, beat the mixture until it holds stiff= peaks, and chill the filling, covered, for 10 minutes. In a small bowl= stir together the cocoa powder and the confectioners' sugar and sift about= half of the mixture evenly over the cake. Cover the cake with a sheet of= wax paper, invert a baking sheet over the paper, and invert the cake onto= the baking sheet. Peel off the foil and wax paper carefully and mound the= filling lengthwise down the center, leaving a 1-inch border at each end. = With a long side facing you and using the wax paper as an aid, roll up the= cake jelly-roll fashion, keeping it wrapped in the wax paper. (The cake= will crack but it will still hold together.)
Chill the cake, wrapped in the wax paper, on the baking sheet for at least 1= hour and up to 2 hours. Transfer the cake to a platter, remove the wax= paper, and trim the ends on the diagonal. The chocolate roll can be= prepared up to this point 1 day in advance and kept covered loosely and= chilled. Sift the remaining cocoa mixture over the cake. Make the garnish= In a chilled small bowl beat the cream with the espresso powder, the= cinnamon, and the confectioners' sugar, sifted, until it just holds stiff= peaks, transfer the mixture to a pastry bag fitted with a small flute tip,= and pipe it decoratively on and around the cake roll. Garnish the roll= with the chocolate coffee